The present invention relates to surgical sponges and surgical and medical dressings.
The present invention relates more specifically to surgical sponges and surgical dressings incorporating light weight absorbent fabrics.
The present invention most particularly relates to a composite crochet knitted and light weight non-woven fabric, some of the non-woven fibers of which, are arranged into a complex configuration, resulting in enhanced capillarity through intimate physical contact with the knit chain-stitch loops formed from hydrophilic yarns.
There exists at the present time a need for a surgical sponge or surgical dressing material suitable for use in the surgical and medical fields, which incorporate highly desirable absorbancy and capillarity properties, and is also light in weight. The desirable properties are those particularly of high capillarity combined with increased absorbancy, with an enlarged capacity for retaining liquids, particularly aqueous wound liquids, such as blood, lymph, and the like.
Woven surgical gauze has been widely incorporated in surgical dressings in which absorbency is an important characteristic. Woven surgical gauze, utilizing cotton, or the like, is generally considered to be the safest absorbent material available for use in operative and post-operative procedures. It is also well recognized that it possesses certain disadvantages. Surgical gauze is an open mesh, loosely woven fabric, composed basically of absorbent cotton fibers tightly twisted into yarns. This physical arrangement of the absorbent fibers enhances the capillarity property, but reduces the total absorbent capacity originally possessed by the fibers when in a loosely associated state. Tests have shown that the total absorbent capacity of loosely associated fibers is several times that of the total absorbent capacity of the same fibers when they are in the tightly twisted state.
Furthermore, as an absorbent material, surgical gauze has the disadvantage of having its absorbent capacity non-uniformly distributed over a wide area, in part because its yarns are arranged relatively widely spaced, and also due, in part, to poorer capillarity characteristics. Thus, the absorbent fibers in the gauze are provided with very little opportunity to remove wound liquids uniformly and rapidly from a field of operation.
On the other hand, the use of the surgical gauze fibers in a loosly associated state is also objectionable, due, in part, to the tendency of the individual loosely-associated fibers to become detached from the total mass of fibers, and to then adhere to the wound, being referred to as "linting out". Furthermore, such a mass of loosely associated fibers would be difficult for a surgeon or nurse to readily manipulate. Likewise, the capillarity of a loosely associated mass of fibers is insufficient to cause absorbed liquids to spread uniformly laterally throughout the mass, resulting in the wound liquid quickly passing through to the back of the absorbent gauze mass.
Further, light weight nonwoven fabrics are generally superior than woven surgical gauze in their absorbency characteristics, in terms of grams of moisture absorbed per gram of fabric material employed. However, when nonwoven fabrics are produced in a weight that is equivalent to heavier surgical gauze, they lack dimensional stability.
In the present invention, by combining, and thereby reinforcing the light weight nonwoven fabric material with a crochet knitted fabric structure, we are able to produce a highly absorbent surgical sponge or dressing structure, having excellent wound liquid absorbtion, high capillarity, dimensional stability and wound conformity characteristics.
Other characteristics that are desirable to incorporate into an improved surgical sponge or dressing, and that are, in fact, some of the important attributes of the present invention, are low "linting out" levels, a high loft, and a gauze-like appearance. Further, the present invention is also characterized by being economical to manufacture and, therefore, highly competitive with surgical cotton gauze.
Further, the present invention surgical sponge material readily lends itself during manufacture to the incorporation of either a visual, or X-ray detectable filament-like element within the composite fabric structure of an exemplary embodiment of the present invention.
In U.S. Pat. No. 2,444,115, there is described a fabric wherein a fibrous web comprising a portion of thermoplastic fibers is bonded to an open-meshed fabric composed of textile yarns, by the use of heat and pressure to develop the adhesive properties of the thermoplastic fibers. Although such combinations are in many ways superior to woven gauze, the fibers in the nonwoven fabric are of uniform distribution, limiting the degree of capillary spread of fluid. The present invention is concerned with improvements in such lightweight absorbent fabrics.
In U.S Pat. No. 3,793,679, there is presented a description of the method of construction of a nonwoven web component similar to one that is utilized in the present invention.
U.S. Pat. No. 3,969,561 contains a description of a non-woven fabric construction and the method of making same, that is similar to the nonwoven fabric component of the present invention.